In networks using software defined networking (SDN), one or more network controllers may manage the control plane of network switches, such as bridges and routers. The network controller may also manage the data plane of the switches by providing flow handling rules to the switches.
In some SDN networks, such as networks implementing an OPENFLOW standard (an “OPENFLOW network”), when a packet is received by a controlled switch, the switch determines if it has a rule applicable to the packet. Such a rule may be defined to apply if a matching criterion is satisfied. For example, the matching criterion may be based on source or destination IP or MAC address, port numbers, transport protocol type, frame type, class of service indicators, or frame control information. If the matching criterion is met, the rule may define various actions for the switch to take. For example, the rule may direct the switch to forward the packet out of a particular port. If the switch does not have a rule applicable to the packet, the switch may transmit all or a portion of the packet to a network controller to allow the network controller to provide a rule applicable to the packet.